Manufacturing a base stock

ABSTRACT

Systems and a method for manufacturing a base stock from a light gas stream are provided. An example method includes oxidizing the light gas stream to form a raw ethylene stream. Water is removed from the raw ethylene stream, and carbon monoxide in the raw ethylene stream is oxidized. Carbon dioxide is separated from the raw ethylene stream, and the raw ethylene stream is oligomerized to form a raw oligomer stream. A light olefinic stream is distilled from the raw oligomer stream and a light alpha olefin is recovered from the light olefinic stream. A heavy olefinic stream is distilled from the raw oligomer stream. The heavy olefinic stream is hydro-processed to form a hydro-processed stream. the hydro-processed stream is distilled to form the base stock.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/721,188, filed on Aug. 22, 2018, the entire contents of which areincorporated herein by reference.

FIELD

The techniques described herein provide systems and methods formanufacturing a lubricant base stock from a methane or ethane feedstock.The methane or ethane feedstock is processed to generate an ethylenestream that is oligomerized and hydro-processed to form the base stock.

BACKGROUND

This section is intended to introduce various aspects of the art, whichmay be associated with examples of the present techniques. Thisdescription is believed to assist in providing a framework to facilitatea better understanding of particular aspects of the present techniques.Accordingly, it should be understood that this section should be read inthis light, and not necessarily as admissions of prior art.

High molecular weight paraffins suitable for the production of highquality lube base stock and distillate fuel are typically in shortsupply and expensive to manufacture. In addition, the oligomerization ofolefins is typically performed with high purity feed streams, such aspolymer grade ethylene.

Some previous research activities have focused on using impure ethylenefeeds to produce polyalphaolefins (PAOs). For example, U.S. PatentApplication Publication No. 2010/0249474 by Nicholas et al. discloses a“process for oligomerizing dilute ethylene.” As described in thepublication, a fluid catalytic cracking process (FCC) may provide adilute ethylene stream, as heavier hydrocarbons are processed. Theethylene in the dilute ethylene stream may be oligomerized using acatalyst, such as an amorphous silica-alumina base with a Group VIII orVIB metal that is resistant to feed impurities such as hydrogen sulfide,carbon oxides, hydrogen and ammonia. About 40 wt. %, or greater, of theethylene in the dilute ethylene stream can be converted to heavierhydrocarbons.

Further, U.S. Patent Application Publication No. 2014/0275669 by Daage,et al., discloses the “production of lubricant base oils from diluteethylene feeds.” As described in this publication, a dilute ethylenefeed, for example, formed while cracking heavier hydrocarbons, may beoligomerized to form oligomers for use as fuels or lubricant base oils.The oligomerization of the impure dilute ethylene is performed with azeolitic catalyst. The zeolitic catalyst is resistant to the presence ofpoisons such as sulfur and nitrogen in the ethylene feed. Diluents suchas light paraffins, may be present without interfering with the process.

The feed used for both processes described above is derived from theprocessing of oil in a fluid catalytic cracker (FCC). In an FCC, heavierhydrocarbons, such as crude oil fractions with a molecular weight ofabout 300 to about 600, or higher, are contacted with a catalyst at hightemperatures to form lower molecular weight compounds. The byproductgases from the FCC include olefins that may be used to form theoligomers.

The oligomerization of blends of ethylene with co-monomers, such as1-hexene, 1-heptene, 1-octene, 1-dodecene, and 1-hexadecene, has beenexplored. For example, U.S. Pat. No. 7,238,764 describes a process forthe co-oligomerization of ethylene and alpha olefins. Theco-oligomerization of the alpha olefins with ethylene is performed inthe presence of a metal catalyst system. The metal catalyst system mayinclude bis-aryliminepyridine MX_(a) complexes, [bis-aryliminepyridineMY_(p).L_(b) ⁺][NC⁻]_(q) complexes, or both. The process is carried outin an ethylene pressure of less than about 2.5 megapascals (MPa).

SUMMARY

In an embodiment, the present invention provides a system formanufacturing a base stock from a light gas stream. The system includesan oxidation reactor configured to form a raw ethylene stream from thelight gas stream, a separation system configured to remove water fromthe raw ethylene stream, a catalytic reactor configured to oxidizecarbon monoxide in the raw ethylene stream, and a removal systemconfigured to remove carbon dioxide from the raw ethylene stream. Anoligomerization reactor is configured to oligomerize the raw ethylenestream to form an oligomer stream. A distillation column is configuredto separate the oligomer stream into a light olefinic stream, whereinthe distillation column is configured to recover a light alpha-olefin,an intermediate olefinic stream, and a heavy olefinic stream. Ahydro-processing reactor is configured to hydro-process the heavyolefinic stream to form a hydro-processed stream, and a productdistillation column is configured to separate the hydro-processed streamto form the base stock.

In another embodiment, the present invention provides a method formanufacturing a base stock from a light gas stream. The method includesoxidizing the light gas stream to form an impure ethylene mixture,removing water from the impure ethylene mixture, oxidizing carbonmonoxide in the impure ethylene mixture, and separating carbon dioxidefrom the impure ethylene mixture. The impure ethylene mixture isoligomerized to form a raw oligomer stream. A light olefinic stream isdistilled from the raw oligomer stream and recovering a light alphaolefin from the light olefinic stream. A heavy olefinic stream isdistilled from the raw oligomer stream, and hydro-processed to form ahydro-processed stream. The hydro-processed stream is distilled to formthe base stock.

In another embodiment, the present invention provides a system formanufacturing a base oil stock from a light gas stream. The systemincludes an oxidation reactor to form a raw ethylene stream from thelight gas stream, a separation system configured to remove water fromthe raw ethylene stream, a catalytic reactor to oxidize carbon monoxidein the raw ethylene stream, and a removal system to remove carbondioxide from the raw ethylene stream. An oligomerization reactor isconfigured to convert the raw ethylene stream to a higher molecularweight stream by contacting the raw ethylene stream with a homogenouscatalyst. A distillation column is configured to recover a lightalpha-olefin (LAO) stream. The distillation column is configured toseparate an intermediate olefinic stream from the higher molecularweight stream and send the intermediate olefinic stream to adimerization reactor or an alkylation reactor. The distillation columnis configured to separate a heavy olefinic stream from the highermolecular weight stream. A hydro-processing reactor is configured todemetallate the heavy olefinic stream, to crack the heavy olefinicstream, to form isomers in the heavy olefinic stream, or to hydrogenateolefinic bonds in the heavy olefinic stream, or any combinationsthereof. A product distillation column is included in the system toseparate the heavy olefinic stream to form a number of base stockstreams.

DESCRIPTION OF THE DRAWINGS

The advantages of the present techniques are better understood byreferring to the following detailed description and the attacheddrawings.

FIG. 1(A) is a simplified block diagram of a system for producing basestocks from a C1 or C2 feedstock, in accordance with examples.

FIG. 1(B) is a simplified block diagram of a recovery system fordehydrating the raw ethylene stream 106 formed from OCM or ODE-C2, inaccordance with examples.

FIG. 1(C) is a simplified block diagram of a CO₂ removal system, inaccordance with examples.

FIG. 2 is a simplified block diagram of another system for producingbase stocks from a C1 or C2 feedstock, in accordance with examples.

FIG. 3 is a process flow diagram of a method for producing base oilstocks from a C1 or C2 feedstock, in accordance with examples.

FIG. 4 is a drawing of related homogeneous catalysts, having differentligands, that may be used for the oligomerization or dimerizationprocesses, in accordance with examples.

FIG. 5 is a plot of the Schultz-Flory distribution of a product thatincludes different carbon numbers, in accordance with examples.

FIG. 6 is a plot of the effect of the change in carbon numbercomposition on a weight fraction of a product as the Schultz-Florydistribution changes, in accordance with examples.

FIGS. 7(A) and 7(B) are plots of a gas chromatograms illustrating thechanges caused by dimerization of an alpha olefin mixture, in accordancewith examples.

FIG. 8 is a series of sequential plots of gas chromatograms illustratingthe change caused by alkylation of a mixture of C14-C24 linearalpha-olefins (LAOS) over a five hour time-span, in accordance withexamples.

FIGS. 9(A) and (B) are gas chromatograms of the alkylation of an alphaolefin mixture after six hours comparing different catalysts, inaccordance with examples.

FIGS. 10(A) and 10(B) are plots of gas chromatograms illustrating thechanges caused by hydroisomerization of an olefin mixture, in accordancewith examples.

FIG. 11 is a plot of DEPT-135 C-13 NMR spectra illustrating the changescaused by hydroisomerization of an alpha olefin mixture, in accordancewith examples.

FIG. 12 is a plot of DEPT-135 C-13 NMR spectra illustrating the changescaused by hydroisomerization of an alkylated alpha olefin mixture, inaccordance with examples.

FIG. 13 is a plot of a simulated distillation of alkylated alpha olefinmixtures, in accordance with examples.

FIG. 14 is a plot of a selective oxidation of CO, in accordance withexamples.

FIG. 15 is a plot of another selective oxidation of CO, in accordancewith examples.

DETAILED DESCRIPTION

In the following detailed description section, specific embodiments ofthe present techniques are described. However, to the extent that thefollowing description is specific to a particular embodiment or aparticular use of the present techniques, this is intended to be forexemplary purposes only and simply provides a description of theexemplary embodiments. Accordingly, the techniques are not limited tothe specific embodiments described below, but rather, include allalternatives, modifications, and equivalents falling within the truespirit and scope of the appended claims.

As hydraulic fracturing provides more low-cost feedstocks, using thesefeedstocks to make more complex products becomes more important.However, upgrading light gas feedstocks may be problematic. The processdescribed herein allows the coproduction of high quality (Group III)base stock and linear alpha olefins from a light gaseous feedstock, suchas a feedstock containing methane, ethane, or both, termed a light gasstream herein. The process begins with the production of an impureethylene stream from light gaseous feedstock using an oxidation process,such as the oxidative dehydration of ethane (ODH-C2) or the oxidativecoupling of methane. The impure ethylene stream is partially purified,for example to remove water, carbon monoxide, and carbon dioxide fromthe oxidation process, among other contaminants.

As used herein, “base stock” or “base oil stock” refers to hydrocarbonsthat may include paraffins, isoparaffins, napthenes, and aromaticcompounds in the lubricant range of molecular weights. The base stocksmay include semi-synthetic or synthetic feedstocks such as linearparaffins and isoparaffins in a lubricant range of molecular weights, inaddition to highly branched molecules useful for chemical applications,such as hydrocarbon fluids. Group I base stocks or base oils are definedas base oils with less than 90 wt. % saturated molecules and/or at least0.03 wt. % sulfur content. Group I base stocks also have a viscosityindex (VI) of at least 80 but less than 120. Group II base stocks orbase oils contain at least 90 wt. % saturated molecules and less than0.03 wt. % sulfur. Group II base stocks also have a viscosity index ofat least 80 but less than 120. Group III base stocks or base oilscontain at least 90 wt. % saturated molecules and less than 0.03 wt. %sulfur, with a viscosity index of at least 120. Other hydrocarbons thatmay be coproduced with base stocks include gasoline, diesel fuels,distillates, and other hydrocarbon fluids.

Further, the base stocks may be referred to as light neutral (LN),medium neutral (MN), and heavy neutral (HN), for example, as determinedby viscosity. The term “neutral” generally indicates the removal of mostnitrogen and sulfur atoms to lower reactivity in the final oil. The basestocks are generally classified by viscosity, measured at 100° C. as akinematic viscosity under the techniques described in ASTM D445. Theviscosity may be reported in millimeters{circumflex over ( )}2/second(centistokes, cSt). The base stocks may also be classified by boilingpoint range, for example, determined by simulated distillation on a gaschromatograph, under the techniques described in ASTM D 2887. It shouldbe noted that the viscosity ranges and boiling point ranges describedherein are merely examples, and may change, depending on the content oflinear paraffins, branched paraffins, cyclic hydrocarbons, and the like.A light neutral base stock may have a kinematic viscosity of about 4 cStto about 6 cSt and may have a boiling point range of about 380° C. toabout 450° C. A medium neutral base stock may have a kinematic viscosityof about 6 cSt to about 10 cSt and a boiling point range of about 440°C. to about 480° C. A heavy neutral base stock may have a kinematicviscosity of about 10 cSt to about 20 cSt, or higher, and a boilingpoint range of about 450° C. to about 565° C.

The production of higher molecular weight linear paraffins andisoparaffins, for example, to form base stocks, from hydrocarbon streamsmay involve numerous steps, which affect the costs for the finalproducts. One example of the production of these compounds is theproduction of syngas, CO and H₂ by steam reforming of methane, followedby methanol synthesis. The methanol may then be converted to olefins viaa methane-to-olefins (MTO) process. The olefins are further oligomerizedto higher molecular weight hydrocarbons. In another example, syngas isproduced for use in Fischer-Tropsch reactions which preferentiallysynthesize linear high molecular weight products. However, these optionsmay be economically problematic due to the need to first produce syngas.

As used herein, a “catalyst” is a material that increases the rate ofspecific chemical reactions under certain conditions of temperature andpressure. Catalysts may be heterogeneous, homogenous, and bound. Aheterogeneous catalyst is a catalyst that has a different phase from thereactants. The phase difference may be in the form of a solid catalystwith liquid or gaseous reactants or in the form of immiscible phases,such as an aqueous acidic catalyst suspended in droplets in an organicphase holding the reactants. A heterogeneous catalyst may be bound, suchas a zeolite bound with alumina or another metal oxide. A homogeneouscatalyst is soluble in the same phase as the reactants, such as anorganometallic catalyst dissolved in an organic solvent with a reactant.

The processed impure feed stream is then introduced to a reaction zonein an oligomerization reactor where a homogeneous catalyst, for example,as described with respect to FIG. 4, is used to generate oligomers in anoligomerization process. The oligomerization reaction forms oligomers byreacting small molecule olefins, such as ethylene and propylene, termedmonomers, to form a short chain or oligomer. The oligomers may includetwo to 50 monomers, or more, depending on the reaction conditions used.The oligomers may be linear alpha-olefins with a Schulz-Flory (S-F)distribution. As used herein, an S-F distribution is a probabilitydistribution that describes the relative ratios of oligomers ofdifferent lengths that occur in an ideal step-growth oligomerizationprocess. Generally, shorter oligomers are favored over longer oligomers.

However, the S-F distribution of the olefinic products may be controlledby the selection of an organic ligand on the catalyst, or through theselection of reaction conditions such as temperature and pressure. Thesechoices may be used to enhance the production of either light LAOs orheavier, base stock range molecules. The product olefins may then besplit into light olefinic (C12−), medium olefinic (C12-C22), and heavyolefinic (C24+) fractions, for example, through conventionaldistillation. It may be noted that the olefinic fractions may not bepure olefins, but may include other compounds with similar boilingpoints, such as paraffinic compounds. The light fraction may include C4,C6, C8, C10, and C12 LAOS, the medium fraction may be sent to adimerization or alkylation reactor using a catalyst selected from avariety of heterogeneous or homogeneous catalysts, and the heavyfraction may be sent to a demetallation zone or stage then to ahydrocracking/hydroisomerization (HDC/HDI) reactor to produce the highquality (Group III) base stock.

The ability to control the S-F distribution makes the targetedproduction of particular products possible. In some examples, an S-Fdistribution of about 0.75 to about 0.91 is targeted to make various waxand base stock products with carbon numbers of at least 24. In otherexamples, an S-F distribution of about 0.83 to about 0.87 is targeted tomake products having about 24 to about 50 carbon atoms, such as lowerviscosity base stocks. In further examples, an S-F distribution of about0.6 to about 0.75 is targeted to make products having about four toabout 22 carbon atoms, such as various linear alpha olefins. Therelation of S-F distribution to various carbon numbers is discussed withrespect to FIG. 6.

For ease of reference, certain terms used in this application and theirmeanings as used herein are set forth. To the extent a term is notdefined herein, it should be given the broadest definition persons inthe pertinent art have given that term as reflected in at least oneprinted publication or issued patent. Further, the present techniquesare not limited by the usage of the terms shown herein, as allequivalents, synonyms, new developments, and terms or techniques thatserve the same or a similar purpose are considered to be within thescope of the present claims.

FIG. 1(A) is a simplified block diagram of a system 100 for producingbase stocks from a C1 or C2 feedstock, in accordance with examples. Theprocess begins with the introduction of the light gaseous feed stream102 to a oxidative reactor 104. Depending on the process used to producethe light gaseous feed stream 102, other treatments may be used forpurification including, for example, filtration, distillation, membranepurification, and the like.

Oxidation Processing

In the oxidation reactor 104, the light gaseous feed stream 102 iscontacted with a catalyst. The catalyst and conditions depend on theprocess. Oxidative coupling of methane (OCM) converts methane and oxygenat high temperatures (>700° C.) over catalysts, and oxidativedehydrogenation of ethane (ODH-C2) converts ethane either at lowertemperatures (350° C.-500° C.) using mixed metal oxides, such asMoVTeNbOx type M1 phase, as a catalyst, or at high temperatures (750°C.) using a selective H₂ combustion catalyst. In one example, theselective H₂ combustion catalyst is an In₂O₃/SiO₂. In another example,the catalyst is an unsupported Bi₂O₃ or manganese oxide. The oxidationis performed in the oxidation reactor 104 with the introduction of anoxygen (or air) stream 105.

The catalysts can be modified with other metal oxides (e.g., MgO/SiO₂)and doped with chemical elements (e.g., La/P), resulting in varyinglifetime, conversion of ethanol and selectivity for ethylene to form araw ethylene stream 106. The mixture of products in the raw ethylenestream 106 from the oxidation reactor 104 may include ethylene, water,methane, ethane, carbon monoxide, hydrogen, and carbon dioxide.

A separation system 108 may be used to separate the water formed in theoxidation process from the raw ethylene stream 106 to form a dehydratedstream 110. The separation system 108 may include a condenser to removewater, for example, as described with respect to FIG. 1(B), a causticcolumn, or a dryer, forming the dehydrated stream 110. After waterremoval, the dehydrated stream 110 may have less than about 1 vol. %water vapor, less than about 0.1 vol. % water vapor, or less than about0.05 vol. %.

The dehydrated stream 110 can be passed to a catalytic reactor 112 forthe selective conversion of carbon monoxide (CO) to carbon dioxide(CO2), as discussed further with respect to the examples. An oxygen feedstream 113 is injected into the catalytic reactor 112 to oxidize the CO.In an example, the catalyst used for the conversion includes thematerial 0.1% Pt/0.3% Co/SiO₂. In another example, the catalyst used forthe conversion includes the material 1.0% Pt/3.0% Co/SiO₂. Theconditions for such selective conversion of CO may be between 25-400 C,or between 50-250 C, and pressure between 50 and 500 psig. The resultingconverted feed 114 may be processed to remove CO₂ using a removal system116, for example, as discussed with respect to FIG. 1(C), forming anoligomerization feed stream 118. When OCM is selected as the oxidationprocess, the resulting impure ethylene feed has about 10-40 wt. %ethylene, about 5-20 wt. % ethane, about 40-85 wt. % methane, about 0-2wt. % H₂, about 0-0.05 wt. % CO, about 0-0.05 wt. % CO₂, and about0-0.05 wt. % H₂O. When ODH of ethane is selected as the oxidationprocess, the resulting impure ethylene feed has about 20-80 wt. %ethylene, about 20-80 wt. % ethane, about 0-5 wt. % methane, about 0-2wt. % Hz, about 0-0.05 wt. % CO, about 0-0.05 wt. % CO₂, and about0-0.05 wt. % H₂O.

Oligomerization

The oligomerization feed stream 118 is provided to an oligomerizationreactor 120, where it may be contacted with a homogeneous catalyst 122,such as an organometallic catalyst. The homogeneous catalyst 122 isgenerally an impurity tolerant organometallic catalyst, such as an Iron(II) pyridine-bis-imide (Fe-PBI), capable of the oligomerization of theoligomerization feed stream 118 to C10+ products, or C25+ products, toproduce diesel, lube, and hydrocarbon fluid molecules, such as the basestocks.

An example of a homogenous catalyst that may be includes an iron (II)pyridine-bis-imine (Fe-PBI) compound having a structure of formula 1:

In formula 1, X is a halogen or hydrocarbyl radical, such as C1. Each Rsubstituent is independently a halogen or hydrocarbyl radical, and eachn is an integer from 1-5 representing the number of R groups present.Each n is 1, 2 or 3. In some examples, n is 2 or 3. Each R is a C1-C10alkyl, or a halogen. In some examples, R is methyl, ethyl or n-propyl.In some examples, at least one R is methyl. In some examples, at leastone R is fluorine. In some examples, Rn comprises one, two, or threesubstituents, wherein each of the substituents is methyl, or fluorine.Each R^(a), and R^(b) are independently a hydrogen, halogen orhydrocarbyl radical. In some examples, each R^(a) is a hydrocarbyl orhydrogen, or a hydrogen. Each R^(b) is a hydrocarbyl, such as a C1-C10alkyl, or methyl.

The homogenous catalyst may include an iron (II) pyridine-bis-imine(Fe-PBI) compound having a structure of formula 2:

In formula 2, each R^(a), R^(b) and X are as defined above, and each Ais independently a substituted aryl group including one, two or three Rsubstituents as defined above.

In some examples, each A is defined by a structure shown in formula 3:

In formula 3, the one position of the phenyl ring is bonded to thenitrogen of the iron (II) pyridine-bis-imine complex, and each R², R³,R⁴, R⁵, and R⁶ are independently C1 to C10 alkyl, halogen or hydrogenradical. In some examples, each R², R³, R⁴, R⁵, and R⁶ are independentlymethyl, ethyl, to n-propyl, fluoro, and hydrogen. In some examples, eachR², R³, R⁴, R⁵, and R⁶ are independently methyl, fluoro and hydrogen. Insome examples, each R² is methyl and each R⁶ is fluoro. In someexamples, each R² is fluoro and each R⁴ is methyl. In some examples,each R² and R⁶ are methyl, and each R⁴ is fluoro. In some examples, eachR² is methyl and each R⁴ is fluoro. In some examples, each R² is methyl.Examples of homogenous catalysts that may be used for theoligomerization are discussed further with respect to FIG. 4.

Generally, the homogenous catalysts are activated. After the complexeshave been synthesized, catalyst systems may be formed by combining themwith activators in any manner known from the literature, including bysupporting them for use in slurry or gas phase polymerization. Thecatalyst systems may also be added to or generated in solutionpolymerization or bulk polymerization (in the monomer). The catalystsystem typically comprises a complex as described above and an activatorsuch as alumoxane or a non-coordinating anion. Activation may beperformed using alumoxane solution including methyl alumoxane, referredto as MAO, as well as modified MAO, referred to herein as MMAO,containing some higher alkyl groups to improve the solubility.Particularly useful MAO can be purchased from Albemarle, typically in a10 wt % solution in toluene. In some examples, the catalyst systememployed uses an activator selected from alumoxanes, such as methylalumoxane, modified methyl alumoxane, ethyl alumoxane, iso-butylalumoxane, and the like.

When an alumoxane or modified alumoxane is used, thecomplex-to-activator molar ratio is from about 1:3000 to 10:1;alternatively 1:2000 to 10:1; alternatively 1:1000 to 10:1;alternatively 1:500 to 1:1; alternatively 1:300 to 1:1; alternatively1:200 to 1:1; alternatively 1:100 to 1:1; alternatively 1:50 to 1:1;alternatively 1:10 to 1:1. When the activator is an alumoxane (modifiedor unmodified), some examples select the maximum amount of activator ata 5000-fold molar excess over the catalyst precursor (per metalcatalytic site). The preferred minimum activator-to-complex ratio is 1:1molar ratio.

Activation may also be performed using non-coordinating anions, referredto as NCA's, of the type described in EP 277 003 A1 and EP 277 004 A1.NCA may be added in the form of an ion pair using, for example,[DMAH]+[NCA]− in which the N,N-dimethylanilinium (DMAH) cation reactswith a basic leaving group on the transition metal complex to form atransition metal complex cation and [NCA]−. The cation in the precursormay, alternatively, be trityl. Alternatively, the transition metalcomplex may be reacted with a neutral NCA precursor, such as B(C6F₅)₃,which abstracts an anionic group from the complex to form an activatedspecies. Useful activators include N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate (i.e., [PhNMe₂H]B(C₆F₅)₄) andN,N-dimethylanilinium tetrakis (heptafluoronaphthyl)borate, where Ph isphenyl, and Me is methyl.

Additionally, activators useful herein include those described in U.S.Pat. No. 7,247,687 at column 169, line 50 to column 174, line 43,particularly column 172, line 24 to column 173, line 53.

Non-coordinating anion (NCA) is defined to mean an anion either thatdoes not coordinate to the catalyst metal cation or that does coordinateto the metal cation, but only weakly. The term NCA is also defined toinclude multicomponent NCA-containing activators, such asN,N-dimethylanilinium tetrakis(pentafluorophenyl)borate, that contain anacidic cationic group and the non-coordinating anion. The term NCA isalso defined to include neutral Lewis acids, such astris(pentafluorophenyl)boron, that can react with a catalyst to form anactivated species by abstraction of an anionic group. An NCA coordinatesweakly enough that a neutral Lewis base, such as an olefinically oracetylenically unsaturated monomer can displace it from the catalystcenter. Any metal or metalloid that can form a compatible, weaklycoordinating complex may be used or contained in the noncoordinatinganion. Suitable metals include, but are not limited to, aluminum, gold,and platinum. Suitable metalloids include, but are not limited to,boron, aluminum, phosphorus, and silicon. A stoichiometric activator canbe either neutral or ionic. The terms ionic activator, andstoichiometric ionic activator can be used interchangeably. Likewise,the terms neutral stoichiometric activator, and Lewis acid activator canbe used interchangeably. The term non-coordinating anion includesneutral stoichiometric activators, ionic stoichiometric activators,ionic activators, and Lewis acid activators.

In an example described herein, the non-coordinating anion activator isrepresented by the following formula (1):(Z)_(d) ⁺(A^(d−))  (1)wherein Z is (L-H) or a reducible Lewis acid; L is a neutral Lewis base;H is hydrogen and (L-H)⁺ is a Bronsted acid; A^(d−) is anon-coordinating anion having the charge d−; and d is an integer from 1to 3.

When Z is (L-H) such that the cation component is (L-H)d+, the cationcomponent may include Bronsted acids such as protonated Lewis basescapable of protonating a moiety, such as an alkyl or aryl, from thecatalyst precursor, resulting in a cationic transition metal species, orthe activating cation (L-H)d+ is a Bronsted acid, capable of donating aproton to the catalyst precursor resulting in a transition metal cation,including ammoniums, oxoniums, phosphoniums, silyliums, and mixturesthereof, or ammoniums of methylamine, aniline, dimethylamine,diethylamine, N-methylaniline, diphenylamine, trimethylamine,triethylamine, N,N-dimethylaniline, methyldiphenylamine, pyridine,p-bromo N,N-dimethylaniline, p-nitro-N,N-dimethylaniline, phosphoniumsfrom triethylphosphine, triphenylphosphine, and diphenylphosphine,oxoniums from ethers, such as dimethyl ether diethyl ether,tetrahydrofuran, and dioxane, sulfoniums from thioethers, such asdiethyl thioethers and tetrahydrothiophene, and mixtures thereof.

When Z is a reducible Lewis acid, it may be represented by the formula:(Ar₃C+), where Ar is aryl or aryl substituted with a heteroatom, or a C₁to C₄₀ hydrocarbyl, the reducible Lewis acid may be represented by theformula: (Ph₃C+), where Ph is phenyl or phenyl substituted with aheteroatom, and/or a C1 to C40 hydrocarbyl. In an example, the reducibleLewis acid is triphenyl carbenium.

Examples of the anion component Ad− include those having the formula[Mk+Qn]d− wherein k is 1, 2, or 3; n is 1, 2, 3, 4, 5 or 6, or 3, 4, 5or 6; n−k=d; M is an element selected from Group 13 of the PeriodicTable of the Elements, or boron or aluminum, and Q is independently ahydride, bridged or unbridged dialkylamido, halide, alkoxide, aryloxide,hydrocarbyl radicals, said Q having up to 20 carbon atoms with theproviso that in not more than one occurrence is Q a halide, and two Qgroups may form a ring structure. Each Q may be a fluorinatedhydrocarbyl radical having 1 to 20 carbon atoms, or each Q is afluorinated aryl radical, or each Q is a pentafluoryl aryl radical.Examples of suitable Ad− components also include diboron compounds asdisclosed in U.S. Pat. No. 5,447,895, which is fully incorporated hereinby reference.

In an example in any of the NCA's represented by Formula 1 describedabove, the anion component Ad− is represented by the formula[M*k*+Q*n*]d*− wherein k* is 1, 2, or 3; n* is 1, 2, 3, 4, 5, or 6 (or1, 2, 3, or 4); n*−k*=d*; M* is boron; and Q* is independently selectedfrom hydride, bridged or unbridged dialkylamido, halogen, alkoxide,aryloxide, hydrocarbyl radicals, said Q* having up to 20 carbon atomswith the proviso that in not more than 1 occurrence is Q* a halogen.

The techniques described herein also relate to a method to oligomerizeolefins comprising contacting olefins (such as ethylene) with a catalystcomplex as described above and an NCA activator represented by theFormula (2):R_(n)M**(ArNHal)_(4-n)  (2)where R is a monoanionic ligand; M** is a Group 13 metal or metalloid;ArNHal is a halogenated, nitrogen-containing aromatic ring, polycyclicaromatic ring, or aromatic ring assembly in which two or more rings (orfused ring systems) are joined directly to one another or together; andn is 0, 1, 2, or 3. Typically the NCA comprising an anion of Formula 2also comprises a suitable cation that is essentially non-interferingwith the ionic catalyst complexes formed with the transition metalcompounds, or the cation is Z_(d) ⁺ as described above.

In an example in any of the NCA's comprising an anion represented byFormula 2 described above, R is selected from the group consisting of C₁to C₃₀ hydrocarbyl radicals. In an example, C₁ to C₃₀ hydrocarbylradicals may be substituted with one or more C₁ to C₂₀ hydrocarbylradicals, halide, hydrocarbyl substituted organometalloid, dialkylamido,alkoxy, aryloxy, alkysulfido, arylsulfido, alkylphosphido,arylphosphide, or other anionic substituent; fluoride; bulky alkoxides,where bulky means C₄ to C₂₀ hydrocarbyl radicals; —SRa, —NR^(a) ₂, and—PR^(a) ₂, where each R^(a) is independently a monovalent C₄ to C₂₀hydrocarbyl radical comprising a molecular volume greater than or equalto the molecular volume of an isopropyl substitution or a C₄ to C₂₀hydrocarbyl substituted organometalloid having a molecular volumegreater than or equal to the molecular volume of an isopropylsubstitution.

In an example in any of the NCA's comprising an anion represented byFormula 2 described above, the NCA also comprises cation comprising areducible Lewis acid represented by the formula: (Ar₃C+), where Ar isaryl or aryl substituted with a heteroatom, and/or a C₁ to C₄₀hydrocarbyl, or the reducible Lewis acid represented by the formula:(Ph₃C+), where Ph is phenyl or phenyl substituted with one or moreheteroatoms, and/or C₁ to C₄₀ hydrocarbyls.

In an example in any of the NCA's comprising an anion represented byFormula 2 described above, the NCA may also comprise a cationrepresented by the formula, (L-H)d+, wherein L is an neutral Lewis base;H is hydrogen; (L-H) is a Bronsted acid; and d is 1, 2, or 3, or (L-H)d+is a Bronsted acid selected from ammoniums, oxoniums, phosphoniums,silyliums, and mixtures thereof.

Further examples of useful activators include those disclosed in U.S.Pat. Nos. 7,297,653 and 7,799,879, which are fully incorporated byreference herein.

In an example, an activator useful herein comprises a salt of a cationicoxidizing agent and a non-coordinating, compatible anion represented bythe Formula (3):(OX^(e+))_(d)(A^(d−))_(e)  (3)wherein OX^(e+) is a cationic oxidizing agent having a charge of e+; eis 1, 2 or 3; d is 1, 2 or 3; and A^(d−) is a non-coordinating anionhaving the charge of d− (as further described above). Examples ofcationic oxidizing agents include: ferrocenium, hydrocarbyl-substitutedferrocenium, Ag⁺, or Pb⁺². Suitable examples of A^(d−) includetetrakis(pentafluorophenyl)borate.

Activators useful in catalyst systems herein include: trimethylammoniumtetrakis(perfluoronaphthyl)borate, N,N-dimethylaniliniumtetrakis(perfluoronaphthyl) borate, N,N-diethylaniliniumtetrakis(perfluoronaphthyl)borate, triphenylcarbeniumtetrakis(perfluoronaphthyl)borate, trimethylammoniumtetrakis(perfluorobiphenyl)borate, N,N-dimethylaniliniumtetrakis(perfluorobiphenyl)borate, triphenylcarbeniumtetrakis(perfluorobiphenyl)borate, and the types disclosed in U.S. Pat.No. 7,297,653, which is fully incorporated by reference herein.

Suitable activators also include: N,N-dimethylanilinium tetrakis(perfluoronaphthyl)borate, N,N-dimethylaniliniumtetrakis(perfluorobiphenyl)borate, N,N-dimethylaniliniumtetrakis(3,5-bis(trifluoromethyl)phenyl)borate, triphenylcarbeniumtetrakis(perfluoronaphthyl)borate, triphenylcarbeniumtetrakis(perfluorobiphenyl)borate, triphenylcarbeniumtetrakis(3,5-bis(trifluoromethyl)phenyl)borate, triphenylcarbeniumtetrakis(perfluorophenyl)borate, [Ph3C+][B(C6F5)4-],[Me3NH+][B(C6F5)4-];1-(4-(tris(pentafluorophenyl)borate)-2,3,5,6-tetrafluorophenyl)pyrrolidinium;and tetrakis(pentafluorophenyl)borate,4-(tris(pentafluorophenyl)borate)-2,3,5,6-tetrafluoropyridine.

In an example, the activator comprises a triaryl carbonium (such astriphenylcarbenium tetraphenylborate, triphenylcarbeniumtetrakis(pentafluorophenyl) borate, triphenylcarbeniumtetrakis-(2,3,4,6-tetrafluorophenyl)borate, triphenyl carbeniumtetrakis(perfluoronaphthyl)borate, triphenylcarbeniumtetrakis(perfluorobiphenyl)borate, triphenylcarbeniumtetrakis(3,5-bis(trifluoromethyl) phenyl)borate).

In an example, two NCA activators may be used in the polymerization andthe molar ratio of the first NCA activator to the second NCA activatorcan be any ratio. In an example, the molar ratio of the first NCAactivator to the second NCA activator is 0.01:1 to 10,000:1, or 0.1:1 to1000:1, or 1:1 to 100:1.

In an example, the NCA activator-to-catalyst ratio is a 1:1 molar ratio,or 0.1:1 to 100:1, or 0.5:1 to 200:1, or 1:1 to 500:1 or 1:1 to 1000:1.In an example, the NCA activator-to-catalyst ratio is 0.5:1 to 10:1, or1:1 to 5:1.

In an example, the catalyst compounds can be combined with combinationsof alumoxanes and NCA's (see for example, U.S. Pat. Nos. 5,153,157;5,453,410; EP 0 573 120 B1; WO 94/07928; and WO 95/14044 which discussthe use of an alumoxane in combination with an ionizing activator, allof which are incorporated by reference herein).

In an example, when an NCA (such as an ionic or neutral stoichiometricactivator) is used, the complex-to-activator molar ratio is typicallyfrom 1:10 to 1:1; 1:10 to 10:1; 1:10 to 2:1; 1:10 to 3:1; 1:10 to 5:1;1:2 to 1.2:1; 1:2 to 10:1; 1:2 to 2:1; 1:2 to 3:1; 1:2 to 5:1; 1:3 to1.2:1; 1:3 to 10:1; 1:3 to 2:1; 1:3 to 3:1; 1:3 to 5:1; 1:5 to 1:1; 1:5to 10:1; 1:5 to 2:1; 1:5 to 3:1; 1:5 to 5:1; 1:1 to 1:1.2.

Alternately, a co-activator or chain transfer agent, such as a group 1,2, or 13 organometallic species (e.g., an alkyl aluminum compound suchas tri-n-octyl aluminum), may also be used in the catalyst systemherein. The complex-to-co-activator molar ratio is from 1:100 to 100:1;1:75 to 75:1; 1:50 to 50:1; 1:25 to 25:1; 1:15 to 15:1; 1:10 to 10:1;1:5 to 5:1; 1:2 to 2:1; 1:100 to 1:1; 1:75 to 1:1; 1:50 to 1:1; 1:25 to1:1; 1:15 to 1:1; 1:10 to 1:1; 1:5 to 1:1; 1:2 to 1:1; 1:10 to 2:1. Whenthe catalyst compounds are ligated metal dihalide compounds, aco-activator is always used when an NCA activator is used.

Other catalysts, including heterogeneous catalyst such as zeolites, maybe used for the oligomerization. Zeolites that may be suitable for thisconversion include, but are not limited to, 10-ring zeolites such asZSM-5 (MFI), ZSM-11 (MEL), ZSM-48 (MRE), and the like, with Si/Al₂ratios from 5 to 500. The zeolites are used in their proton form and mayor may not be promoted with metals by ion exchange or impregnation. Inaddition, the binder used during formulation can have an effect on theyield and product slate. Other reaction chemistries may be used for theoligomerization, such as free radical reactions. In some examples, thesealternate catalysts and reaction chemistries are used with furtherseparation steps to remove other products before or after dimerizationor alkylation processes.

The oligomerization process can be performed as a single step process ora two-step process. In a single step process, all of the oligomerizationis performed in a single stage or in a single reactor in theoligomerization reactor 120. The oligomerization feed stream 118 isintroduced into the single stage generally as a gas phase feed. Theoligomerization feed stream 118 is contacted with the homogeneouscatalyst 122 under effective oligomerization conditions. A solvent, suchas hexane, cyclohexane, or toluene, may be used for the oligomerizationprocess, and recycled. The impure ethylene feed may be contacted withthe homogeneous catalyst 122 at a temperature of 20° C. to 300° C. Insome examples, the reaction temperature is at least 25° C., or at least50° C., or at least 100° C., and is 250° C. or less, or 225° C. or less.The total pressure can be from 1 atm (100 kPa) to 200 atm (20.2 MPa). Insome examples, the total pressure is 100 atm (10.1 MPa) or less. In someexamples, the oligomerization feed is contacted with the catalyst at ahydrogen partial pressure that is at least 1% of the total pressure,such as at least 5% of the total pressure or at least 10% of the totalpressure or up to about 50% on a volumetric basis. The reaction forms araw oligomer stream 124 that can then be fractionated in a distillationcolumn 126. An optional step of to quench the catalyst may be used,which consists of using a base, either aqueous or organic, before thefractionation.

In the distillation column 126, three streams may be separated from theraw oligomer stream 124. These may include a light olefinic stream 128,an intermediate olefinic stream 130 and a heavy olefinic stream 132. Itmay be noted that the olefinic streams 128, 130, and 132 may not becomposed of 100% olefinic compounds, but may include a number of othercompounds, such as paraffinic compounds, that are removed in the sameboiling point ranges as the olefinic compounds.

The light olefinic stream 128 may include, for example, linearalpha-olefins having from about four carbon atoms to about 10 carbonatoms and unreacted ethylene. Further, as higher molecular weightcompounds are formed, the amounts of paraffinic compounds may increaseas well. The light olefinic stream 128 may be processed to separate anunreacted ethylene stream 134 which may be combined with theoligomerization feed stream 118 and provided to the oligomerizationreactor 120. After separation of the unreacted ethylene stream 134, theremaining stream 136 may be processed to recover the lightalpha-olefins, for example, having less than about 12 carbon atoms. Thisseparation may be performed by a distillation column, a cold box, orother separation methods.

The intermediate olefinic stream 130 may be provided to a dimerizationreactor 138. As an example, the intermediate olefinic stream 130 mayinclude compounds having about 12 carbon atoms to compounds having about22 carbon atoms, although this may be adjusted based on the takeoffpoint in the distillation column 126. In the dimerization reactor 138,the intermediate olefinic stream 130 may be contacted with a homogenousor heterogeneous catalyst to be dimerized to form carbon compoundshaving about 24 carbon atoms to about 44 carbon atoms. The reaction maybe run at a temperature of about 50° C. to about 400° C., and a pressureof about 50 psig to about 2000 psig. The dimerized stream 140 may bereturned to the distillation column 126, in which lower carbon numbercompounds, such as unreacted compounds having about 12 carbon atoms toabout 22 carbon atoms, may be further sent to the dimerization reactor138 for processing.

The heavy olefinic stream 132 may have at least about 24 carbon atoms.To lower the amounts of contaminants, as well as to upgrade the finalproducts, the heavy olefinic stream 132 may be provided to ahydro-processing reactor 142 to remove contaminants and improve productproperties, such as cold flow properties. For example, hydrotreatment ormild hydrocracking can be used for removal of contaminants, andoptionally to provide some viscosity index uplift, while hydrocrackingand hydroisomerization, termed catalytic HDC/HDI, may be used to improvecold flow properties.

Hydro-Processing

As used herein, “hydro-processing” includes any hydrocarbon processingthat is performed in the presence of hydrogen. The hydrogen may be addedto the hydro-processing reactor 142 as a hydrogen treat stream 144. Thehydrogen treat stream 144 is fed or injected into a vessel or reactionzone or hydro-processing zone in which the hydro-processing catalyst islocated. The hydrogen treat stream 144 may be pure hydrogen or ahydrogen-containing gas, which is a gas stream containing hydrogen in anamount that is sufficient for the intended reactions. The hydrogen treatstream 144 may include one or more other gasses, such as nitrogen andlight hydrocarbons, that do not interfere with or affect either thereactions or the products. Impurities, such as H, S and NH, areundesirable and would typically be removed from the hydrogen treatstream 144 before it is conducted to the reactor. The hydrogen treatstream 144 introduced into a reaction stage may include at least 50 vol.% hydrogen or at least 75 vol. % hydrogen. The products of thehydro-processing reactor 142, termed a hydro-processed stream 146, mayhave lower contaminants, including metals and heteroatom compounds, aswell as improved viscosities, viscosity indices, saturates content, lowtemperature properties, volatilities and depolarization, and the like.

Various types of hydro-processing can be used in the production of fuelsand base stocks, such as hydroconversion, hydrocracking, hydrogenation,hydrotreating, hydrodesulfurization, hydrodenitrogenation,hydrodemetallation, and hydroisomerization, among others. Typicalprocesses include a demetallation process to remove metallic remnants ofthe catalyst. Further, a catalytic dewaxing, orhydrocracking/hydroisomerization (HDC/HDI) process, may be included tomodify viscosity properties or cold flow properties, such as pour pointand cloud point. The hydrocracked or dewaxed feed can then behydrofinished, for example, to saturate olefins and aromatics from theheavy olefinic stream 132. In addition to the above, a hydrotreatmentstage can also be used for contaminant removal. The hydrotreatment ofthe oligomer feed to remove contaminants may be performed prior to orafter the hydrocracking or the HDC/HDI.

In the discussion below, a stage in the hydro-processing reactor 142 cancorrespond to a single reactor or a plurality of reactors. In someexamples, multiple reactors can be used to perform one or more of theprocesses, or multiple parallel reactors can be used for all processesin a stage. Each stage or reactor may include one or more catalyst bedscontaining hydro-processing catalyst. Note that a catalyst bed in thediscussion below may refer to a partial physical catalyst bed. Forexample, a catalyst bed within a reactor could be filled partially witha hydrocracking catalyst and partially with an HDC/HDI catalyst. Forconvenience in description, even though the two catalysts may be stackedtogether in a single catalyst bed, the hydrocracking catalyst and theHDC/HDI catalyst can each be referred to conceptually as separatecatalyst beds.

As an example, the hydro-processing reactor 142 shown in FIG. 1(A)includes a demetallation reactor 142A and ahydrocracking/hydroisomerization (HDC/HDI) reactor 142B, shown asseparate reactors or stages.

Hydrodemetallation

The demetallation reactor 142A includes a demetallation catalyst andoperates at about 200-500° C. and 50-1200 psi. The demetallation reactorremoves metals in the homogeneous catalyst, such as Fe and Al, from theorganic components, which are deposited on the solid catalysts. Thedemetallation reactor is typically used for the removal of metals inpetroleum oil. The metals in petroleum oil exists as metal complexes,much like the metals in the homogeneous catalysts.

Hydroisomerization/Hydrocracking (HDC/HDI)

In the HDC/HDI reactor 142B, suitable HDC/HDI (dewaxing) catalysts mayinclude molecular sieves such as crystalline aluminosilicates, orzeolites. In various examples, the molecular sieve includes ZSM-5,ZSM-22, ZSM-23, ZSM-35, ZSM-48, SAPO-11, zeolite Beta, or zeolite Y, orincludes combinations thereof, such as ZSM-23 and ZSM-48, or ZSM-48 andzeolite Beta. Molecular sieves that are selective for dewaxing byisomerization, as opposed to cracking, may be used, such as ZSM-48,ZSM-23, SAPO-11 or any combinations thereof. The molecular sieves mayinclude a 10-member ring 1-D molecular sieve. Examples include EU-1,ZSM-35 (or ferrierite), ZSM-11, ZSM-57, NU-87, SAPO-11, ZSM-48, ZSM-23,and ZSM-22. Some of these materials may be more efficient, such as EU-2,EU-11, ZBM-30, ZSM-48, or ZSM-23. Note that a zeolite having the ZSM-23structure with a silica to alumina ratio of from 20:1 to 40:1 may bereferred to as SSZ-32. Other molecular sieves that are isostructuralwith the above materials include Theta-I, NU-10, EU-13, KZ-1, and NU-23.The HDC/HDI catalyst may include a binder for the molecular sieve, suchas alumina, titania, silica, silica-alumina, zirconia, or a combinationthereof, for example alumina and titania or silica and zirconia,titania, or both.

In various examples, the catalysts according to the disclosure furtherinclude a hydrogenation catalyst to saturate olefins and aromatics,which may be termed hydrofinishing herein. The hydrogenation catalysttypically includes a metal hydrogenation component that is a Group VIand/or a Group VIII metal. In some examples, the metal hydrogenationcomponent is a Group VIII noble metal. For example, the metalhydrogenation component may be Pt, Pd, or a mixture thereof. Further,the metal hydrogenation component may be a combination of a non-nobleGroup VIII metal with a Group VI metal. Suitable combinations caninclude Ni, Co, or Fe with Mo or W, or, in some examples, Ni with Mo orW.

The metal hydrogenation component may be added to the catalyst in anyconvenient manner. For example, the metal hydrogenation component may becombined with the catalyst using an incipient wetness. In thistechnique, after combining a zeolite and a binder, the combined zeoliteand binder can be extruded into catalyst particles. These catalystparticles may then be exposed to a solution containing a suitable metalprecursor. In some examples, metal can be added to the catalyst by ionexchange, where a metal precursor is added to a mixture of zeolite (orzeolite and binder) prior to extrusion.

The amount of metal in the catalyst may be at least about 0.1 wt. %based on catalyst, or at least about 0.15 wt. %, or at least about 0.2wt. %, or at least about 0.25 wt. %, or at least about 0.3 wt. %, or atleast about 0.5 wt. % based on catalyst. The amount of metal in thecatalyst may be about 20 wt. % or less based on catalyst, or about 10wt. % or less, or about 5 wt. % or less, or about 2.5 wt. % or less, orabout 1 wt. % or less. For examples where the metal is Pt, Pd, anotherGroup VIII noble metal, or a combination thereof, the amount of metalmay be from about 0.1 to about 5 wt. %, about 0.1 to about 2 wt. %, orabout 0.25 to about 1.8 wt. %, or about 0.4 to about 1.5 wt. %. Forexamples where the metal is a combination of a non-noble Group VIIImetal with a Group VI metal, the combined amount of metal may be fromabout 0.5 wt. % to about 20 wt. %, or about 1 wt. % to about 15 wt. %,or about 2.5 wt. % to about 10 wt. %.

The HDC/HDI catalysts may also include a binder. In some examples, theHDC/HDI catalysts may use a low surface area binder. A low surface areabinder represents a binder with a surface area of about 100 m²/g orless, or 80 m²/g or less, or about 70 m²/g or less. The amount ofzeolite in a catalyst formulated using a binder can be from about 30 wt.% zeolite to about 90 wt. % zeolite relative to the combined weight ofbinder and zeolite. In some examples, the amount of zeolite may be atleast about 50 wt. % of the combined weight of zeolite and binder, suchas at least about 60 wt. % or from about 65 wt. % to about 80 wt. %.

A zeolite can be combined with binder in any convenient manner. Forexample, a bound catalyst can be produced by starting with powders ofboth the zeolite and binder, combining and mulling the powders withadded water to form a mixture, and then extruding the mixture to producea bound catalyst of a desired size. Extrusion aids can also be used tomodify the extrusion flow properties of the zeolite and binder mixture.

Process conditions in a catalytic HDC/HDI zone in a may include atemperature of from about 200 to about 450° C., or from about 270 toabout 400° C., a hydrogen partial pressure of from about 1.8 MPag toabout 34.6 MPag (about 250 psig to about 5000 psig), or from about 4.8MPag to about 20.8 MPag, and a hydrogen circulation rate of from about35.6 m³/m³ (200 SCF/B) to about 1781 m³/m³ (10,000 SCF/B), or from about178 m³/m³ (1000 SCF/B) to about 890.6 m³/m³ (5000 SCF/B). In otherexamples, the conditions can include temperatures in the range of about343° C. (600° F.) to about 435° C. (815° F.), hydrogen partial pressuresof from about 3.5 MPag-20.9 MPag (about 500 psig to 3000 psig), andhydrogen treat gas rates of from about 213 m³/m³ to about 1068 m³/m³(1200 SCF/B to 6000 SCF/B). These latter conditions may be suitable, forexample, if the HDC/HDI stage is operating under sour conditions, e.g.,in the presence of high concentrations of sulfur compounds.

The liquid hourly space velocity (LHSV) can vary depending on the ratioof hydrocracking catalyst used to hydroisomerization catalyst in theHDC/HDI catalyst. Relative to the combined amount of hydrocracking andhydroisomerization catalyst, the LHSV may be from about 0.2 h⁻¹ to about10 h⁻¹, such as from about 0.5 h⁻¹ to about 5 h⁻¹ and/or from about 1h⁻¹ to about 4 h⁻¹. Depending on the ratio of hydrocracking catalyst tohydroisomerization catalyst used, the LHSV relative to only the HDC/HDIcatalyst can be from about 0.25 h⁻¹ to about 50 h⁻¹, such as from about0.5 h⁻¹ to about 20 h⁻¹, or from about 1.0 h⁻¹ to about 4.0 h⁻¹.

Hydrotreatment Conditions

Hydrotreatment may be used to reduce the sulfur, nitrogen, and aromaticcontent of the heavy olefinic stream 132, for example, removing nitrogencompounds from the oligomerization catalyst or sulphur compounds fromthe feedstock. The catalysts used for hydrotreatment may includehydro-processing catalysts that include at least one Group VIIInon-noble metal (Columns 8-10 of IUPAC periodic table), such as Fe, Co,or Ni, or Co or Ni, and at least one Group VI metal (Column 6 of IUPACperiodic table), such as Mo or W. Such hydro-processing catalysts mayinclude transition metal sulfides that are impregnated or dispersed on arefractory support or carrier such as alumina or silica. The support orcarrier itself typically has no significant or measurable catalyticactivity. Substantially carrier- or support-free catalysts, commonlyreferred to as bulk catalysts, generally have higher volumetricactivities than their bound counterparts.

In addition to alumina or silica, other suitable support or carriermaterials can include, but are not limited to, zeolites, titania,silica-titania, and titania-alumina. Suitable aluminas include porousaluminas, such as gamma or eta forms, having average pore sizes fromabout 50 to about 200 Angstrom (A), or about 75 to about 150 Å; asurface area from about 100 to about 300 m²/g, or about 150 to about 250m²/g; and a pore volume of from about 0.25 to about 1.0 cm³/g, or about0.35 to about 0.8 cm³/g. Generally, any convenient size, shape, or poresize distribution for a catalyst suitable for hydrotreatment of adistillate (including lubricant base oil) boiling range feed in aconventional manner may be used. Further, more than one type ofhydro-processing catalyst can be used in one or multiple reactionvessels. A Group VIII non-noble metal, in oxide form, may be present inan amount ranging from about 2 wt. % to about 40 wt. %, or from about 4wt. % to about 15 wt. %. A Group VI metal, in oxide form, can typicallybe present in an amount ranging from about 2 wt. % to about 70 wt. %,or, for bound catalysts, from about 6 wt. % to about 40 wt. % or fromabout 10 wt. % to about 30 wt. %. These weight percentages are based onthe total weight of the catalyst. Suitable metal catalysts includecobalt/molybdenum (for example, including about 1-10% Co as oxide andabout 10-40% Mo as oxide), nickel/molybdenum (including about 1-10% Nias oxide and about 10-40% Co as oxide), or nickel/tungsten (includingabout 1-10% Ni as oxide and about 10-40% W as oxide) on alumina, silica,silica-alumina, or titania, among others.

The hydrotreatment is carried out in the presence of hydrogen, forexample, from the hydrogen treat stream 144. Hydrotreating conditionscan include temperatures of about 200° C. to about 450° C., or about315° C. to about 425° C.; pressures of about 250 psig (1.8 MPag) toabout 5000 psig (34.6 MPag) or about 300 psig (2.1 MPag) to about 3000psig (20.8 MPag); liquid hourly space velocities (LHSV) of about 0.1hr⁻¹ to about 10 hr⁻¹; and hydrogen to treat rates of about 200 SCF/Btu(35.6 m³/m³), to 10,000 SCF/Btu (1781 m³/m³) or about 500 (89 m³/m³) toabout 10,000 SCF/B (1781 m³/m³) or about 3000 psig (3.5 MPag-20.9 MPag),and hydrogen treat gas rates of from about 213 m³/m³ to about 1068 m³/m³(1200 SCF/Btu 6000 SCF/Btu).

Hydrofinishing and Aromatic Saturation Process

In some examples, a hydrofinishing stage, an aromatic saturation stage,or both may be used. These stages are termed finishing processes herein.Finishing processes may improve color and stability in a final productby lowering the amounts of unsaturated or oxygenated compounds in thefinal product streams. The finishing may be performed in thehydro-processing reactor 142 after the last hydrocracking orhydroisomerization stage. Further, the finishing may occur afterfractionation of a hydro-processed stream 146 in a product distillationcolumn 148. If finishing occurs after fractionation, the finishing maybe performed on one or more portions of the fractionated product. Insome examples, the entire effluent from the last hydrocracking orHDC/HDI process can be finished prior to fractionation into individualproduct streams.

In some examples, the finishing processes, including hydrofinishing andaromatic saturation, refer to a single process performed using the samecatalyst. Alternatively, one type of catalyst or catalyst system can beprovided to perform aromatic saturation, while a second catalyst orcatalyst system can be used for hydrofinishing. Typically the finishingprocesses will be performed in a separate reactor from the HDC/HDI orhydrocracking processes to facilitate the use of a lower temperature forthe finishing processes. However, an additional hydrofinishing reactorfollowing a hydrocracking or HDC/HDI process, but prior tofractionation, may still be considered part of a second stage of areaction system conceptually.

Finishing catalysts can include catalysts containing Group VI metals,Group VIII metals, and mixtures thereof. In an example, the metals mayinclude a metal sulfide compound having a strong hydrogenation function.The finishing catalysts may include a Group VIII noble metal, such asPt, Pd, or a combination thereof. The mixture of metals may also bepresent as bulk metal catalysts wherein the amount of metal is 30 wt. %or greater based on the catalyst. The metals and metal compounds may bebound, for example, on a metal oxide. Suitable metal oxide supportsinclude low acidic oxides such as silica, alumina, silica-aluminas ortitania, or, in some examples, alumina.

The catalysts for aromatic saturation may include at least one metalhaving relatively strong hydrogenation function on a porous support.Typical binding materials include amorphous or crystalline oxidematerials such as alumina, silica, and silica-alumina. The bindingmaterials to may also be modified, such as by halogenation orfluorination. The metal content of the catalyst may be as high as 20 wt.% for non-noble metals. In an example, a hydrofinishing catalyst mayinclude a crystalline material belonging to the M41S class or family ofcatalysts. The M41S family of catalysts are mesoporous materials havinghigh silica content. Examples include MCM-41, MCM-48 and MCM-50.Examples include MCM-41, MCM-48, MCM-49, and MCM-50. Other catalyststhat may be used include Beta, Y, and other large pore zeolites(12-member ring MR and up). If separate catalysts are used for aromaticsaturation and hydrofinishing, an aromatic saturation catalyst can beselected based on activity or selectivity for aromatic saturation, whilea hydrofinishing catalyst can be selected based on activity forimproving product specifications, such as product color and polynucleararomatic reduction.

Hydrofinishing conditions can include temperatures from about 125° C. toabout 425° C., or about 180° C. to about 280° C., a hydrogen partialpressure from about 500 psig (3.4 MPa) to about 3000 psig (20.7 MPa), orabout 1500 psig (10.3 MPa) to about 2500 psig (17.2 MPa), and an LHSVfrom about 0.1 hr⁻¹ to about 5^(hr-1) LHSV, or, in some examples, 0.5hr⁻¹ to 1.5 hr⁻¹. Additionally, a hydrogen treat gas rate of from about35.6 m³/m³ to about 1781 m³/m³ (200 SCF/B to 10,000 SCF/B) can be used.

Fractionation and Products

After hydro-processing, the hydro-processed oligomers in thehydro-processed stream 146 can be fractionated in the productdistillation column 148. Any number of fractions may be isolated,including, for example, a distillate stream 150 that may includehydrocarbon fluids, such as gasoline, naphtha, diesel, or a distillatefuel fraction, among others. Fractions that form base stocks forlubricants and other hydrocarbon products, may be isolated, including,for example, a light neutral stream 152, a medium neutral stream 154,and a heavy neutral stream 156.

A bottoms stream 158 may also be isolated. In some examples, the bottomsstream 158 is returned to the hydro-processing reactor 142 for furtherprocessing.

FIG. 1(B) is a simplified block diagram of a recovery system 108 fordehydrating the raw ethylene stream 106 formed from OCM or ODE-C2, inaccordance with examples. Like numbered items are as described withrespect to FIG. 1. The recovery system 108 may be as simple as acondenser 160. In this example, the raw ethylene stream 106, includingethylene, water from the oxidation process, and any water from the lightgaseous feed stream 102 is fed to the condenser 160. A coolant-in stream162 may include water from a cooling tower, or lower temperaturecoolants for enhanced removal of water, such as propane, ammonia, orother coolants. A coolant-out stream 164 may return the coolant, warmedby condensing water, to a coolant system. The condensed water may beremoved in a water stream 166, while the dehydrated stream 110 exitsthrough a different port on the vessel and is provided to downstreamprocessing units, such as the catalytic reactor 112. As describedherein, other water removal systems may be used, such as flash tanks,caustic systems, absorption systems, and the like. In some examples, thepurification system may remove other compounds, such as sulfur compoundsand nitrogen compounds, lowering poison concentrations before theoligomerization process.

FIG. 1(C) is a simplified block diagram of a CO₂ removal system 116, inaccordance with examples. In this example, the converted feed 114 istreated in a counter-current contacting tower 168. In thecounter-current contacting tower 168, the converted feed 114 is flowedup the tower, while a lean absorbent stream 170 is flowed down thetower. The lean absorbent stream 170 may be released in thecounter-current contacting tower 168 from spray nozzles 171, while otherstructures, such as trays, may be used to increase contact time. A richadsorbent stream 172 exits the counter-current contacting tower 168 atthe bottom, while the oligomerization feed stream 118 exits the top.Other systems may be used for CO₂ removal, such as pressure swingadsorption units, and the like.

FIG. 2 is a simplified block diagram of another system 200 for producingbase stocks from a C1 or C2 feedstock, in accordance with examples. Likenumbered items are as described with respect to FIGS. 1(A) and 1(B). Theintermediate olefinic stream 130 is not limited to being upgraded bydimerization, but may be upgraded by other processes, such asalkylation.

As used herein, “alkylation” refers to a process in which a feed streamcontaining olefins, such the intermediate olefinic stream 130, isreacted with another stream containing hydrocarbons, such as a mixedxylenes or naphthalene stream 174, among others, in an alkylationreactor 176. The process converts at least a portion of the olefiniccompounds to higher molecular compounds. An alkylation reactor may reactthe feed streams 174 and 130 in the presence of a catalyst, for example,an acid, such as sulfuric acid or hydrofluoric acid, or a solid acid,such as a zeolite, for example zeolite Y, zeolite beta, and zeolite ofthe MWW family, among others. The alkylation may be run at a temperatureof about 50° C. to about 250° C., and a pressure of about 300 psig toabout 1000 psig. The process provides an alkylated stream 178 that maybe processed in the alkylation reactor 176 to remove acid and othercontaminants before being provided to a separation or distillationcolumn 180.

In the distillation column 180, light or unreacted compounds, or alights stream, may be separated into an unreacted stream 182 and blendedwith the intermediate olefinic stream 130 to be fed back into thealkylation reactor 176. A heavy product stream 184, or a heavies stream,may be separated out and provided to an HDC/HDI reactor 142B.

FIG. 3 is a process flow diagram of a method 300 for producing base oilstocks from a C1 or C2 feedstock, in accordance with examples. Themethod 300 begins at block 302, with the oxidation of a C1 or C2 streamto form an impure ethylene mixture. As described herein, the impureethylene mixture may include ethylene, water, carbon monoxide, carbondioxide, and contaminants, depending on the oxidation process.

At block 304, the impure ethylene stream may be dehydrated. This may beperformed by passing the impure ethylene stream through a condenser toremove water from the impure ethylene stream. Other actions may beperformed for the purification, including, for example, passing theoutput stream from the condenser through a coldbox to remove anyremaining traces of water or other contaminants.

At block 306, carbon monoxide in the impure ethylene mixture isselectively oxidized to form carbon dioxide. At block 308, the carbondioxide is removed from the impure ethylene mixture, for example, byadsorption in a counter-current tower or a pressure swing adsorptionunit.

At block 310, the ethylene stream may be oligomerized to form a rawoligomer stream. As described herein, this may be performed bycontacting the ethylene stream with a homogenous catalyst to form theraw oligomer stream, wherein the raw oligomer stream has a substantialconcentration of linear alpha olefins.

At block 312, a heavy olefinic stream is distilled from the intermediatestream. At block 314, the heavy olefinic stream is hydro-processed toform a hydro-processed stream. In the hydro-processing, the heavyolefinic stream may be hydrodemetallated to remove any traces ofcatalyst remaining from the oligomerization. The heavy olefinic streammay then be hydrocracked to form lower molecular weight compounds, forexample, having a broader distribution. The heavy olefinic stream may behydroisomerized to form a distribution of different isomers. Further,the heavy olefinic stream may be finished to decrease unsaturated andaromatic compounds in the hydro-processed stream.

At block 316, the hydro-processed stream is distilled to form the basestock. Distilling the hydro-processed stream may include separating adistillate stream, a naphtha stream, or both from the hydro-processedstream. Further, distilling the hydro-processed stream may includeforming a heavy neutral oil stock stream, a medium neutral oil stockstream, or a light neutral oil stock stream, or any combinationsthereof.

EXAMPLES Example 1: Linear Alpha Olefins of Different Schulz-FloryMolecular Distribution May be Produced from Impure Ethylene Using aHomogeneous Catalyst

The molecular distribution may be controlled by the catalyst, forexample, through the ligands. FIG. 4 is a drawing 400 of relatedhomogeneous catalysts, having different ligands, that may be used forthe oligomerization or dimerization processes, in accordance withexamples. The catalysts are labeled A-D, and are described further withrespect to the oligomerization reactions. Catalyst E may be used in thedimerization process.

The tests of the catalysts in the oligomerization process were performedin a 500 milliliter (mL) autoclave. 100 mL toluene solution containing20 micromoles (μmol) catalyst and 4000 μmol MAO activator was charged tothe autoclave. Then a predetermined amount of N₂, or a mixture of H₂ andN₂ in some examples, as described with respect to Tables 1-3, wascharged into the autoclave to bring the autoclave to a preset pressure.The autoclave was then heated to 50° C. before ethylene was introduced.The reaction was exothermic and ethylene addition was controlled to keepthe temperature below about 120° C. and a final total pressure of about400 psi. The oligomerization reaction was allowed to proceed forapproximately 30 minutes.

The autoclave was then cooled to room temperature and overhead gaspressure was released via opening of a valve. The reaction product, inthe form of a solution or suspension was then recovered, quenched withan aqueous HCl solution, and the aqueous phase containing Fe and Al wasdiscarded. The reaction product was analyzed via gas chromatography (GC)and nuclear magnetic resonance (NMR) techniques.

The gas chromatography analysis for ethylene oligomers was performedusing a method that enabled coverage up to C30. The column was 30 mlong, with an inner diameter of 0.32 millimeters and a packing of 0.25μm, available as a HP-5 column from Agilent. The carrier gas wasnitrogen. The injector was held at a temperature of 150° C. and 10 psi.A 50 to 1 split ratio was used with a 121 mL per minute (mL/min) totalflow rate and an injection size of 1-5 μL. The column oven was set to a50° C. initial temp with a 10° C./min ramp rate to a 320° C. finaltemperature. It was held at the 320° C. temperature for 8 minutes givinga total run time of 35 minutes. The detector was a flame ionizationdetector held at 300° C., using a 30 mL/min flow of hydrogen, a 250mL/min flow of air, and a 25 mL/min makeup stream of nitrogen. The gaschromatography analysis for dimerization or alkylation products wasperformed using a high temperature method to enable coverage up to C100.The column was 6 m long, with an inner diameter of 0.53 millimeters anda packing of 0.15 μm, available as a MXT-1 SimDist column from Restekcompany of State College, Pa. The carrier gas was nitrogen. The injectorwas held at a temperature of 300° C. and 0.9 psi. A 15 to 1 split ratiowas used with a 27.4 mL per minute (mL/min) total flow rate and aninjection size of 1 μL. The column oven was set to an 80° C. initialtemp with a 15° C./min ramp rate to a 400° C. final temperature. It washeld at the 400° C. temperature for 15 minutes giving a total run timeof 36.3 minutes. The detector was a flame ionization detector held at300° C., using a 40 mL/min flow of hydrogen, a 200 mL/min flow of air,and a 45 mL/min makeup stream of nitrogen.

The C-13 NMR analysis was performed using a Bruker 400 MHz Advance IIIspectrophotometer. The samples were dissolved in chloroform-D (CDCl₃) ortoluene-D8 in a 5 mm NMR tube at concentrations of between 10 to 15 wt.% prior to being inserted into the spectrophotometer. The C-13 NMR datawas collected at room temperature (20° C.). The spectra were acquiredwith time averaging to provide a signal to noise level adequate tomeasure the signals of interest. Prior to data analysis, spectra werereferenced by setting the chemical shift of the CDCl₃ solvent signal to77.0 ppm.

H-1 NMR data was collected at room temperature. The data was recordedusing a maximum pulse width of 45 degree, 8 seconds between pulses andsignal averaging of 120 transients.

The analyses confirmed that the products were mostly linearalpha-olefins (LAOS) having Schulz-Flory (S-F) distributions. The S-Fdistribution constant, α, was determined by averaging the molar ratios:C16/C14; C14/C12; and C12/C10 in the product, as determined by gaschromatography.

The information in Table 1 shows the basic comparison betweenoligomerizations performed using catalysts A-D. For these runs, thereaction conditions included about 200 psi or ethylene, about 200 psi ofhydrogen, a reaction temperature of about 80 to 100° C., 100 mL oftoluene (as a catalyst solvent), 20 μmol of catalyst, and a ratio of 200mol/mol of activator (co-catalyst) to catalyst, such as the MAOactivators described herein.

TABLE 1 Comparison of oligomerization by catalyst A-D % Linear AlphaAlpha % Branched % Linear Example Catalyst Value Olefin* Olefins*Paraffin* X1 A 0.339 66.6 22.1 1.6 X2 B 0.667 92.9 5.2 1.2 X3 C 0.82896.0 1.1 2.4 X4 D 0.947 34.5 0.2 64.7 *Presented in C12 fraction asdetermined by gas chromatography and mass spectrometry

Catalyst B was chosen to determine the effects of changing the ratio ofhydrogen to nitrogen on the reaction. The results are shown in Table 2.For these runs, the reaction conditions included about 200 psi orethylene, about 200 psi of hydrogen or a mixture of hydrogen andnitrogen, a reaction temperature of about 80 to 100° C., 100 mL oftoluene, 20 μmol of catalyst, and a ratio of 200 mol/mol of activator(co-catalyst) to catalyst. As can be seen by the results in Table 2,changing the hydrogen to nitrogen ratio has relatively small effects onthe operation of the catalyst.

TABLE 2 Comparison of oligomerization under changing ratios of hydrogenand nitrogen using catalyst B % Linear % Branched % Linear ExampleCatalyst H2/N2, psi Alpha Value Alpha Olefin* Olefins* Paraffin* X2 B200/0  0.667 92.9 5.2 1.2 X5 B  20/180 0.666 92.2 6.3 0.8 X6 B  2/1980.698 89.2 8.6 1.1 *Presented in C12 fraction as determined by gaschromatography and mass spectrometry

Catalyst C was chosen to determine the effects of changing the solventfor the reaction. The results are shown in Table 3. For these runs, thereaction conditions included about 200 psi or ethylene, about 200 psi ofhydrogen or a mixture of hydrogen and nitrogen, a reaction temperatureof about 80 to 100° C., 100 mL of a solvent as identified in Table 3,20-40 μmol of catalyst, and a ratio of 100-200 mol/mol of activator(co-catalyst) to catalyst.

TABLE 3 Comparison of oligomerization using different solvents andcatalyst C % Linear Alpha % Branched % Linear Example Catalyst SolventAlpha Value Olefin* Olefins* Paraffin* X3 C Toluene 0.828 96.0 1.1 2.4X7 C Isohexane 0.825 92.2 1.28 3.7 X9 C Cyclohexane 0.826 91.4 1.87 3.9*Presented in C12 fraction as determined by gas chromatography and massspectrometry

The results of the runs in Tables 1-3 indicate that controlling theligand of the Fe-complex, may be used to control both theparaffin/olefin ratio and the S-F distribution product composition. Itmay also be noted that the oligomerization using catalysts A-D istolerant of a large amount of H₂ and a variety of aromatic, naphthenic,and paraffinic hydrocarbons as solvents.

FIG. 5 is a plot 500 of the Schultz-Flory distribution of a product thatincludes different carbon numbers, in accordance with examples. Theweight fraction of the Schulz-Flory product distribution withexperimentally obtained a values may be plotted against the carbonnumber in the product. The same data can be recast to show lumpedfraction distribution as a function of a value.

FIG. 6 is a plot 600 of the effect of the change in carbon numbercomposition on a weight fraction of a product as the Schultz-Florydistribution changes, in accordance with examples. The plot 600 showsC24-, C24-C50, and C52+ fractions as a function of a value, indicatingthat the lube molecule range C24-C50 has a maximum value of about 40 wt.% at an a value around 0.88. This further illustrates that the lube/LAOsplit may be effectively controlled by using different catalysts thatoffer different a values.

Example 2: Dimerizing an Intermediate Olefinic Stream (C14-C24) intoLube Range Molecules

The dimerization may be performed by either heterogeneous catalysts,such as solid acid catalysts, or homogeneous organometallic catalysts.For example, solid acids include proton form zeolite, acid treated clay,amorphous silica-alumina, acid form ion-exchange resins, and variousWO3/ZrO2 mixed metal oxides.

To test the dimerization, a 19 g mixture of C14-C24 linear alpha olefinswas treated with 200 mg of Catalyst E and 1 mL of MAO at roomtemperature overnight. The resulting mixture was diluted with hexane andthen hydrolyzed with aqueous HCl.

FIGS. 7(A) and 7(B) are plots of gas chromatograms illustrating thechanges caused by dimerization 702 of the alpha olefin mixture, inaccordance with examples. The plots 700 are of the starting material 704and the product 706. The plot of the starting material 704 shows a firstset of peaks 708 from the C14-C24 linear alpha-olefins (LAOS) generatedby a homogeneous catalyst, such as catalyst E.

After dimerization, a second set of peaks 710 show a significantdecrease in the amount of C14-C24 LAOS, as well as some broadening,indicating reaction of the LAOS. A new set of peaks 712 is present afterthe reaction, corresponding to C26 to C52 (and higher) olefins. Thisillustrates the effectiveness of dimerization in increasing themolecular weight of the LAOS. Other techniques, such as alkylation, maybe used to increase the molecular weight of the LAOS.

After dimerization, a second set of peaks 710 show a significantdecrease in the amount of C14-C24 LAOS, as well as some broadening,indicating reaction of the LAOS. A new set of peaks 712 is present afterthe reaction, corresponding to C26 to C52 (and higher) olefins. Thisillustrates the effectiveness of dimerization in increasing themolecular weight of the LAOS. Other techniques, such as alkylation, maybe used to increase the molecular weight of the LAOS.

Example 3: Alkylation of Aromatic Compounds with C12-C22 Linear AlphaOlefins into Lube Range Molecules

Both liquid and solid acid catalysts may be used for the aromaticalkylation of LAOs with various aromatic compounds. Solid acids includeproton form zeolite, acid treated clay, amorphous silica-alumina, acidform ion-exchange resins, and various WO3/ZrO2 mixed metal oxides. Thealkylkation is described further with respect to FIG. 8.

FIG. 8 is a series of sequential plots 800 of gas chromatogramsillustrating the change caused by alkylation of a mixture 802 of C14-C24linear alpha-olefins (LAOS) over a five hour time-span, in accordancewith examples. During the alkylation the LAOs are reacted with a mixtureof xylenes over an acid clay catalyst at a temperature of about 115° C.The alkylation both broadens the distributions of the LAOS, as xylenesare added, and increases the molecular weights, as multiple LAO chainsmay be added to a single xylene.

FIGS. 9(A) and (B) are gas chromatograms of the product of alkylation ofan alpha olefin mixture after six hours comparing different catalyst, inaccordance with examples. FIG. 9(A) is a plot of a gas chromatogram ofthe reaction of C14-C24 LAOs with mixed xylenes over an MCM-49 catalystat 115° C. for six hours. FIG. 9(B) is a plot of a gas chromatogram ofthe reaction of C14-C24 LAOs with mixed xylenes over an acid clay at115° C. for six hours. While both catalysts perform the alkylation, theacid clay catalyst shown in FIG. 9(B) is more effective at makingmaterials with higher molecular weights.

Example 4: Hydroisomerizing Lube Range Olefin Molecules to Lube Oil

The hydroisomerization of olefins may broaden the molecular weightdistributions of the olefins, improving characteristics such as pourpoint, VI, and others. This may be performed by a number of acidcatalysts, such as the ZSM-48 catalyst described in the synthesisprocedure below.

Preparation of Formulated ZSM-48 Catalyst

To form a bound ZSM-48 catalyst, 65 parts ZSM-48 zeolite crystals arecombined with 35 parts pseudoboehmite alumina dry powder, on a calcineddry weight basis. The ZSM-48 and the pseudoboehmite alumina dry powderare placed in a muller or a mixer and mixed for about 10 to 30 minutes.Sufficient water is added to the ZSM-48 and alumina during the mixingprocess to produce an extrudable paste.

The extrudable paste is formed into a 1/16 inch quadralobe extrudateusing an extruder. After extrusion, the 1/16th inch quadralobe extrudateis dried at a temperature ranging from about 250° F. (about 120° C.) toabout 325° F. (about 163° C.). After drying, the dried extrudate isheated to about 1000° F. (about 538° C.) under flowing nitrogen. Theextrudate is then cooled to ambient temperature and humidified withsaturated air or steam. After the humidification, the extrudate is ionexchanged with about 0.5 to about 1 N ammonium nitrate solution. Theammonium nitrate solution ion exchange is repeated. The ammonium nitrateexchanged extrudate is then washed with deionized water to removeresidual nitrate prior to calcination in air. After washing the wetextrudate, it is dried. The exchanged and dried extrudate is thencalcined in a nitrogen/air mixture to about 1000° F. (about 538° C.).Following calcination, the extrudate was exposed to steam at about 700°F. (about 371° C.) for about three hours.

The formulated ZSM-48 catalyst was added to the dimerized productdescribed with respect to FIG. 7(A) in Example 2. The mixture was heatedin an closed autoclave at hydroisomerization condition of about 200-250°C. and about 500-1000 psi H₂ for 1-5 days.

FIGS. 10(A) and 10(B) are plots of gas chromatograms illustrating thechanges caused by hydroisomerization 1002 of an olefin mixture 1004, inaccordance with examples. As described with respect to FIG. 7(A), theolefin mixture 1004 includes C14-C24 olefins 1006 and C28-C52 olefins1008. The gas chromatogram of the reaction products 1010 in is shown inFIG. 7(B). The comparison of the GC traces of the materials beforehydroisomerization (FIG. 10(A)) and after hydroisomerization (FIG.10(B)) are shown below, which clearly indicate isomerization of themolecules (broadening of peaks).

FIG. 11 is a plot 1100 of the DEPT-135 C-13 NMR spectra illustrating thechanges caused by hydroisomerization 1102 of an alpha olefin mixture, inaccordance with examples. As used herein, DEPT is an acronym fordistortionless enhancement by polarization transfer. The technique isused to determine the multiplicity of carbon atoms substitution withhydrogen. The DEPT-135 experiment is carried out using a pulse with aflip angle of 135°. The DEPT-135 C-13 NMR spectra of the products ofhydroisomerization of dimerized C14-C24 LAOs showed the presence ofisolated methyl (CH3, ˜20 ppm) branching 1104, and the associatedmethine (CH, ˜32 ppm) carbon 1106 and methylene carbons 1108 (CH2, ˜27and ˜37 ppm) adjacent to the methine (CH) carbon.

TABLE 4 Comparisons of dimerized and hydroisomerized products. ExampleX9 X10 X11 X12 Description Hydro- Hydro- Dimerized isomerized Dimerizedisomerized C14-C24 LAO X9 C14 + LAO X11 Mn by GPC 412 374 464 405 Mw byGPC 466 437 658 463 PD by GPC 1.13 1.17 1.42 1.14 Tm by DSC, ° C. 25.46.4 47.0 30.2 Tg by DSC, ° C. −16.5 −66.5 −5.4 −25.2

In Table 4, Mn is the number averaged molecular weight, Mw is the weightaveraged molecular weight, and PD is the polydispersity, calculated asMw/Mn. The GPC or gel permeation chromatography is calibrated withpolyethylene standards. DSC is differential scanning calorimetry. Tm isthe melting point or crystallization temperature of the material and Tgis the glass transition temperature of the material.

TABLE 5 Comparisons of alkylated and hydroisomerized products. ExampleX14 X15 X16 X17 Description Xylene Hydro- Xylene Hydro- alkylatedisomerized alkylated isomerized C14-C24 LAOs X14 C14 + LAO X16 Mn by GPC289 299 455 369 Mw by GPC 313 322 1051 510 PD by GPC 1.08 1.07 2.31 1.39Tm by DSC, ° C. −2.1 −11.6 68 −19.9 Tg by DSC, ° C. −58.9 −83.9 −56−78.2

-   -   The abbreviations are as defined with respect to Table 4.

FIG. 12 is a plot 1200 of the DEPT-135 C-13 NMR spectra illustrating thechanges caused by hydroisomerization 1202 of an alkylated alpha olefinmixture, in accordance with examples. Similarly, the DEPT-135 C-13 NMRspectra before and after hydroisomerization of xylene alkylated withC14-C24 LAOs showed the presence of isolated methyl (CH3, ˜20 ppm)branching 1204, its associated methine (CH, ˜32 ppm) carbon 1206 andmethylene carbons (CH2, ˜27 and ˜37 ppm) 1208 adjacent to the methine(CH) carbon. The reduction of CH3 (˜19 ppm) 1210 on xylenes isattributed to the hydrogenation of the aromatic ring.

FIG. 13 is a plot 1300 of a simulated distillation of alkylated alphaolefin mixtures, in accordance with examples. The simulated distillationwas run using the techniques described in ASTM D2887-16a “Standard TestMethod for Boiling Range Distribution of Petroleum Fractions by GasChromatography.” The boiling range of the hydroisomerized materials,such as Example X17 in Table 5, as determined by simulated distillationcover two standard base stock examples, Stnd 1: GTL 3.6 and Stnd 2: GTL6.0 cSt. This indicates that the suggesting the possibility offractionating into different viscosity grades of Group III+ base stocks.

Example 5: Selective Oxidation of Carbon Monoxide

Most organometallic complex-based oligomerization catalysts are poisonedby CO. Accordingly, CO may need to be removed from the impure ethylenestream. CO may be removed in syngas reforming by reaction with water,allowing the production of hydrogen (CO+H₂O═CO₂+H₂). In the process COis selectively oxidized to CO₂ and H₂ is not. However, the presentexample demonstrates that CO can be converted to CO₂ without theoxidation of H₂ and ethylene. As a result, the hydrogenation of ethyleneobserved at high CO conversion may not be an issue as H₂ is not presentin a feed stream produced by OCM or ODE-C2.

The catalysts were tested in a 7 mm diameter stainless steel fixed bedreactor, which was set in a 5 kg brass heat sink. An electric furnacemaintained catalyst temperatures at 30-300° C. Each catalyst was formedinto 40-60 mesh pellets, and mixed with quartz to obtain catalyst loadsof 0.05-0.5 g in a 10 cm length of the reactor. Gases were metered bymass flow controllers (available from Brooks). Gas feeds included (1)Hydrogen, (2) a mixture of 98% Ethylene with 1.75% Propylene and 0.25%CO, and (3) a mixture of 2% Oxygen with 98% Nitrogen. Water wasdelivered by pumps (available from Teledyne-Isco) and vaporized incapillary tubes at 180° C. to achieve steady flow. Typical feedcompositions comprised about 50% H₂, 50% olefin, and 0.125% CO. Someruns included water and N₂ at 2-8% and O₂ at 0.1-0.3%. A gaschromatograph (GC, available from Wasson-ECE) detected all feeds andhydrocarbon products. H₂O, CO₂, and other oxygenates were not detected.

The selective oxidation of carbon monoxide was shown over Pt/Co/SiO₂catalyst at 10 WHSV and 100 psig of 48% H₂, 47% ethylene (C₂═), 0.8%propylene (C3=), 0.12% CO, 0.1% O₂, 5% N₂, and 3% H₂O.

FIG. 14 is a plot 1400 of a selective oxidation of CO, in accordancewith examples. The specific catalyst used in the example shown in FIG.14 included a composition of 0.1% Pt/0.3% Co/SiO₂, formed fromPt(NH₃)₄(NO₃)₂, Co(NO₃)₂, and Arginine, which was impregnated on acatalyst support of Davisil 646. As shown in FIG. 14, CO conversion ashigh as 90% at 130° C., using this catalyst.

FIG. 15 is a plot 1500 of another selective oxidation of CO, inaccordance with examples. The specific catalyst using an example shownin FIG. 15 included a composition of 1.0% Pt/3.0% Co/SiO2,Pt(NH₃)₄(NO₃)₂, Co(NO₃)₂, and Arginine, which was impregnated on acatalyst support of Davisil 646. As shown in FIG. 15, the CO conversionwas as high as 85% at 75° C. using this catalyst.

In both cases the conversion was achieved with limited to no conversionof ethylene. With optimization of catalyst and reaction conditions, itis feasible that much higher conversion may be achievable. If tracequantities of CO remain after CO conversion, commercially availableselective adsorption technologies, such as BASF's Cu based adsorptiontechnology, may be used to remove <20 PPM levels of CO down to ppblevels.

Embodiments

The embodiments of the present techniques include any combinations ofthe examples in the following numbered paragraphs.

1. A system for manufacturing a base stock from a light gas stream,including an oxidation reactor configured to form a raw ethylene streamfrom the light gas stream, a separation system configured to removewater from the raw ethylene stream, a catalytic reactor configured tooxidize carbon monoxide in the raw ethylene stream, and a removal systemconfigured to remove carbon dioxide from the raw ethylene stream. Anoligomerization reactor is configured to oligomerize the raw ethylenestream to form an oligomer stream. A distillation column is configuredto separate the oligomer stream into a light olefinic stream, whereinthe distillation column is configured to recover a light alpha-olefin,an intermediate olefinic stream, and a heavy olefinic stream. Ahydro-processing reactor is configured to hydro-process the heavyolefinic stream to form a hydro-processed stream, and a productdistillation column is configured to separate the hydro-processed streamto form the base stock.

2. The system of Embodiment 1, wherein the oxidation reactor isconfigured to perform an oxidative coupling of methane (OCM).

3. The system of either of Embodiments 1 or 2, wherein the oxidationreactor is configured to perform an oxidative dehydration of ethane(ODE).

4. The system of any of Embodiments 1 to 3, wherein the removal systemincludes an amine column.

5. The system of any of Embodiments 1 to 4, including a dimerizationreactor configured to dimerize the intermediate olefinic stream andreturn a dimerized stream to the distillation column.

6. The system of any of Embodiments 1 to 5, including an alkylationreactor configured to alkylate the intermediate olefinic stream andprovide an alkylated stream to an alkylation distillation column.

7. The system of Embodiment 6, wherein the alkylation distillationcolumn is configured to separate an unreacted olefin stream from thealkylated stream and return the unreacted olefin stream to thealkylation reactor.

8. The system of any of Embodiments 1 to 7, wherein the oligomerizationreactor is configured to use a homogenous catalyst.

9. The system of Embodiment 8, wherein the homogenous catalyst includesan iron (II) pyridine-bis-imine (Fe-PBI) catalyst including a structureof

wherein Rn includes one, two, or three substituents, and wherein thesubstituents include CH₃, F, or both.

10. The system of any of Embodiments 1 to 9, wherein thehydro-processing reactor includes a demetallation unit.

11. The system of any of Embodiments 1 to 10, wherein thehydro-processing reactor includes a hydrocracking unit.

12. The system of any of Embodiments 1 to 11, wherein thehydro-processing reactor includes a hydroisomerization unit.

13. The system of any of Embodiments 1 to 12, wherein the productdistillation column is configured to separate the hydro-processed streaminto a distillate stream including naphtha, a heavy neutral stream, amedium neutral stream, and a light neutral stream.

14. A method for manufacturing a base stock from a light gas stream,including oxidizing the light gas stream to form an impure ethylenemixture, removing water from the impure ethylene mixture, oxidizingcarbon monoxide in the impure ethylene mixture, and separating carbondioxide from the impure ethylene mixture. The impure ethylene mixture isoligomerized to form a raw oligomer stream. A light olefinic stream isdistilled from the raw oligomer stream and recovering a light alphaolefin from the light olefinic stream. A heavy olefinic stream isdistilled from the raw oligomer stream, and hydro-processed to form ahydro-processed stream. The hydro-processed stream is distilled to formthe base stock.

15. The method of Embodiment 14, including distilling an intermediateolefinic stream from the raw oligomer stream.

16. The method of Embodiment 15, including dimerizing the intermediateolefinic stream to form a dimerized stream, and distilling the dimerizedstream with the raw oligomer stream.

17. The method of Embodiment 15, including alkylating the intermediateolefinic stream to form an alkylated stream, distilling the alkylatedstream to form a lights stream and a heavies stream, combining thelights stream with the intermediate olefinic stream to form a combinedstream, and alkylating the combined stream.

18. The method of Embodiment 17, including hydro-processing the heaviesstream.

19. The method of any of Embodiments 14 to 18, wherein oligomerizing theimpure ethylene mixture includes contacting the impure ethylene mixturewith a homogenous catalyst including an iron (II) pyridine-bis-imineincluding a structure of

wherein Rn includes one, two, or three substituents, and wherein thesubstituents include CH₃, F, or both.

20. The method of any of Embodiments 14 to 19, including separating anunreacted ethylene stream from the impure ethylene mixture, andoligomerizing the unreacted ethylene stream with the impure ethylenemixture.

21. The method of any of Embodiments 14 to 20, wherein hydro-processingthe heavy olefinic stream includes hydrocracking the heavy olefinicstream.

22. The method of any of Embodiments 14 to 21, wherein hydro-processingthe heavy olefinic stream includes hydroisomerizing the heavy olefinicstream.

23. The method of any of Embodiments 14 to 22, wherein distilling thehydro-processed stream includes separating a distillate stream, anaphtha stream, or both from the hydro-processed stream.

24. The method of any of Embodiments 14 to 23, wherein distilling thehydro-processed stream includes forming a heavy neutral oil stockstream, a medium neutral oil stock stream, or a light neutral oil stockstream, or any combinations thereof.

25. A system for manufacturing a base oil stock from a light gas stream,including an oxidation reactor to form a raw ethylene stream from thelight gas stream, a separation system configured to remove water fromthe raw ethylene stream, a catalytic reactor to oxidize carbon monoxidein the raw ethylene stream, and a removal system to remove carbondioxide from the raw ethylene stream. An oligomerization reactor isconfigured to convert the raw ethylene stream to a higher molecularweight stream by contacting the raw ethylene stream with a homogenouscatalyst. A distillation column is configured to recover a lightalpha-olefin (LAO) stream. The distillation column is configured toseparate an intermediate olefinic stream from the higher molecularweight stream and send the intermediate olefinic stream to adimerization reactor or an alkylation reactor. The distillation columnis configured to separate a heavy olefinic stream from the highermolecular weight stream. A hydro-processing reactor is configured todemetallate the heavy olefinic stream, to crack the heavy olefinicstream, to form isomers in the heavy olefinic stream, or to hydrogenateolefinic bonds in the heavy olefinic stream, or any combinationsthereof. A product distillation column is included in the system toseparate the heavy olefinic stream to form a number of base stockstreams.

26. The system of Embodiment 25, wherein the dimerization reactor isconfigured to dimerize the intermediate olefinic stream to form adimerized stream and return the dimerized stream to the distillationcolumn.

27. The system of either of Embodiments 25 or 26, wherein the alkylationreactor is configured to alkylate the intermediate olefinic stream toform an alkylated stream.

28. The system of Embodiment 27, including an alkylation distillationcolumn configured to separate the alkylated stream into a reacted streamand an unreacted stream, and return the unreacted stream to thealkylation reactor.

29. The system of any of Embodiments 25 to 28, wherein the homogenouscatalyst includes an iron (II) pyridine-bis-imine (Fe-PBI) compoundincluding a structure of

wherein Rn includes one, two, or three substituents, and wherein thesubstituents include CH₃, F, to or both.

While the present techniques may be susceptible to various modificationsand alternative forms, the embodiments discussed above have been shownonly by way of example. However, it should again be understood that thetechniques is not intended to be limited to the particular embodimentsdisclosed herein. Indeed, the present techniques include allalternatives, modifications, and equivalents falling within the truespirit and scope of the appended claims.

The invention claimed is:
 1. A method for manufacturing a base stockfrom a light gas stream, comprising: oxidizing the light gas stream toform an impure ethylene mixture; removing water from the impure ethylenemixture to form a water-depleted impure ethylene mixture; oxidizingcarbon monoxide in the water-depleted impure ethylene mixture to form aCO-depleted impure ethylene mixture; separating carbon dioxide from theCO-depleted impure ethylene mixture to form a CO₂-depleted impureethylene mixture; oligomerizing the CO₂-depleted impure ethylene mixtureto form a raw oligomer stream; distilling a light olefinic stream, anintermediate olefinic stream, and a heavy olefinic stream from the rawoligomer stream; recovering a light alpha olefin from the light olefinicstream; subjecting the heavy olefinic stream to hydrodemetallation toform a first hydro-processed stream; alkylating the intermediateolefinic stream to form an alkylated stream; distilling the alkylatedstream to form a lights stream and a heavies stream; recycling thelights stream to the intermediate olefinic subjecting the firsthydro-processed and the heavies stream to hydrocracking and/orhydroisomerization to form a second hydro-processed stream; anddistilling the second hydro-processed stream to form the base stock. 2.The method of claim 1, wherein said oligomerizing the impure ethylenemixture comprises contacting the impure ethylene mixture with ahomogenous catalyst comprising an iron (II) pyridine-bis-iminecomprising a structure of:

wherein Rn comprises one, two, or three substituents; and wherein thesubstituents comprise CH₃, F, or both.
 3. The method of claim 1,comprising: separating an unreacted ethylene stream from the rawoligomer stream; and recycling the unreacted ethylene stream to theCO₂-depleted impure ethylene mixture.
 4. The method of claim 1, whereinsaid distilling the second hydro-processed stream comprises separating adistillate stream, a naphtha stream, or both from the secondhydro-processed stream.
 5. The method of claim 1, wherein saiddistilling the second hydro-processed stream comprises forming a heavyneutral oil stock stream, a medium neutral oil stock stream, or a lightneutral oil stock stream, or any combinations thereof.